Projector lens, shift & throw calculation help

SeanRo

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I'm doing the calcs for my first projector purchase and would like help on what specs I am looking for. Here are my proposed angles:

Projector angle to top of screen: 6 degrees down from horizontal
Projector angle to bottom of screen: 23 degrees down from horizontal
Projector distance from screen: 4.3m

Eyes angle to top of screen : 16.5 degrees up from horizontal (I read that >20 degrees causes fatigue)
Eyes angle to bottom of screen : 11 degrees down from horizontal
Eyes distance from screen: 3.2m

Screen width: 3.2m

Q. if I want the projector to switch from 16:9 to 2.35:1 on detected content, what projector feature should I look for?
Q. if I want the projector to shift the image down as in my sketchup, what do I look for?
Q. are these reasonable angles/distances for a projector to work with?

Thanks in advance!

ht-projector-angles.png
 
For maximum flexibility on positioning, a projector with lens shift will allow quite a lot of movement in where the image is displayed, whether above, below, or even off to one side! So any projector that has lens shift will accommodate your 6 degree angle to the screen comfortably.

When you say a projector that can detect and switch between 16:9 and 2.35:1, I’m guessing you’re planning on using a CIH (constant image height) screen with a 2.35:1 ratio - so your 16:9 images will have black bars either side. For this, you need a zoom function.

Most web-sites selling projectors will have ‘throw’ calculators which will enable you to get an idea of what will work. I’ve just thrown in your throw distance of 4.3m into an online calculator for the Epson 9400 for example, and you’ll be able to display an image from anywhere between roughly 1.5m wide, to nearly 3.2m wide - so pretty flexible. Whether it will flip from one aspect ratio to another without user intervention, I don’t know, and I’d suggest it might throw its own issues into the pot if you’re watching anything directed by Nolan!

Best of luck! Just remember, once the projector goes up, all work stops, you’ll spend more time watching movies than working on the room - ask me how I know! :rolleyes: :D
 

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